Aircraft wing fuel tanks are integral to the structure. The wing spars, the primary load-bearing structures, form the forward and aft extremities of the tanks, while the wing ribs form the lateral extremities. The ribs are sometimes used to divide the wings into multiple fuel tanks. The wing skins form the upper and lower caps of the fuel tanks. Fuel tank sealant is applied to all these parts during manufacturing to ensure the tank will not leak.
For the purpose of this discussion, the fuel tank areas include most of the wingbox with the structural elements described above. No fuel is carried outside those elements in the wing, i.e., in the cavities formed by the leading-edge fairings and trailing-edge that give the wing its beautiful aerodynamic shapes.
The methodology applies for integral fuel tanks in the horizontal stabilizer, where so equipped. These include the Airbus A330/A340 and A380, as well as the Boeing 747–400 and, finally, the 747–8 should its horizontal fuel tanks ever be reactivated.
- The integral wing tank of an Airbus A320neo jetliner built into its wingbox. [1]
- The stringers, which give the skins shape and attach them to the ribs and spars, can be seen here, asking with a rib, both spars, some plumbing and the all-important sealant (the dark grey/black silicon outlining the stringers, and covering many fasteners).
- The Airbus A380’s fuel tank arrangement.
- The aircraft has fuel capacity for 310,000 litres of Jet A.
- 68,190 imperial gallons
- 81,890 US gallons
- The aircraft has fuel tanks in the wings and trimmable horizontal stabilizer.
- ©?
- The scale of the A380’s wings is hugely impressive.
- © Airbus
- Sometimes maintenance is required of equipment in the tanks, or indeed, structural inspections are required of the structure. For that there are these access panels on the wing lower surfaces.[2]
Post Production Edit – #1:
The person who asked this question has troubling thoughts about liquid volumetric sizes/capacities. I will attempt to show what 310,000 litres looks like. If we visualise this, half the problem goes away.
The starting point for this problem is that 1,000 litres of liquid is equal to 1 cubic metre:
1,000 litres = 1m³
The Airbus A380–800 has a mean aerodynamic chord length of 12.3 metres. This is the average aerodynamic length of the ribs¹ across the wingbox, and is a useful figure for approximating what the dimensions of a box containing 310,000 litres might look like:
With that figure at hand, we can look at the Airbus A380–800’s wing span and other details. The aircraft has a span of just under 80 metres. It has no centre wing fuel tank – i.e., no fuel tank carried in the fuselage.
Additionally, the A380–800 has a fuselage diameter of 7.15 metres.
Let’s say that the tanked portion of the A380–800 is 80 metres less 7.15 metres, and less a little more, leaving just 70 metres of possible tanked wing.
The maths follows as such:
By the way, a cubic metre = 1m x 1m x 1m.
1,000 litres = 1m³
310,000 litres = 310m³
310m³ ÷ 12.3m ÷ 70m = 0.36m
Therefore, the average depth of such a tank is 36 centimetres.
That is a believable figure. Considering the wingtip depth of a 737 Classic airplane is a little more than half that figure.
Of course, the tanked space of the wing is a complex shape, best described using integral mathematics, but they basic idea I’ve presented here stands. The dummy math gets the point across pretty simplistically.
Footnotes
[2] Aircraft Manual Magnetic Fuel Level Indicator
Author – Paulo Martins
